This invention relates to tufting machines and more particularly to a hook driving assembly for cut pile tufting machines.
Tufting machines incorporate a multiplicity of yarn carrying needles which reciprocate cyclically to penetrate a backing material and cooperate with a multiplicity of loopers or hooks to form loop pile or cut pile respectively in the backing material. In a cut pile tufting machine the loops which are formed by the cooperation of the individual needles and hooks are severed on the hooks to provide cut pile. The means for severing the loops comprise a knife that acts against the lower edge of the loop-penetrating blade of the respective hook adjacent the throat or neck of the hook remote from the bill.
The hooks are driven to oscillate in a path having forward and backward motion for seizing a loop from the respective needles. The knives are mounted on an oscillating shaft to oscillate relative to the hooks. In a conventional construction, the hook mounting bar is mounted to pivot about a remote axis by an arm of significant length, the arm being curved so as to extend around the knife drive shaft which is positioned below the hook bar. Motion of the hook bar is derived from a hook drive shaft which, through an eccentric and drive linkage, oscillates the hook bar about the remote pivot. Examples of such a drive mechanism are illustrated in U.S. Pat. Nos. 3,973,505 (Pritchard); 4,134,347 (Jolley et al) and 4,834,005 (Bagnall).
The long rocker arm in the aforesaid construction in addition to providing the required oscillating path to the hooks also aids in supporting the hooks and, because of its rigidity, provides support for the lateral forces applied by the knives against the hooks. However, the system because of the extremely long and rigid arm has a very high oscillating mass. Such an oscillating mass even when effectively balanced to a large degree, as in the aforesaid Pritchard patent, has a limiting effect on the speed at which the tufting machine may operate.